Method and apparatus for coating metallic articles.



J. D. HATHAWAY. METHOD AND APPARATUS FOR CQATING METALLIC ARTICLES.

APPLICATION FILED SEPT-20. l9l6.

Patented Nov. 2?', 191?.

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JOSEPH D. HATHAWAY, OF MONTREAL, QUEBEC,

CANADA, ASSIGNOR, BY MESWE ASSIGNMENTS, T0v WESTERN ELECTRIC COMPANY, INCORPORATED, Olli NEW YORK, lll'. Y., A. CORPORATION OIF NEW YORK. i

METHOD ANI) APPARATUS FOR COAllIIil't'll METALJDIG ARTICLES.

specification of Lettera rarest.

restanten new. er, iler e.

Application tiled September 20, 191e. Serial No. MM5?.

ada, have invented certain new and useful para- I Improvements in the Methods and Ap tus for Coating Metallic Articles, of which the following is a full, clear, concise, and exact description.

This invention relates to an improved method and apparatus for coating metallic articles, ,and more particularly to an improved and eiiicient method and apparatus for applying to metallic articles a very thin and uniform coating of another gnetal. More specifically the invention relates to an improved method and apparatus for applying a very thin coatin of tin to cop ei: wire and `then subjecting tle coated con uctor to a coating of insulatingenamel.

One of the objects of this invention is'to produce a method and apparatus for covering articles with a coating of another metal is so finely distributed that the coating wi 1 have no tendency to run when subjected to a coating of baked enamel at a temperature as high, or higher than the melting temperature of the coating metal.

Another object of the invention is to produce an improved method and apparatus for procuring coated wiresof the exact size or gage desired, by utilizing an uncpated wire which is slightly over size, subjecting it to a coating of another metal and then draw.,- ing the coated wire to the'exact size desired.

A further object of this invention is the production of an improved method and apparatus for materially increasing thespeed at which metallic coatings are ap lied to wires and to applya coating whic .is exceeding thin and which is evenly distributed.

Another object is the pro uction of a method andv apparatus for applying to copper conductors a very thin, smooth and evenly distributed'coatmg. of tin and then applying to said tinned wirea smooth and even coating of baked insulating enamel.

Other features of this invention will liecome apparent from the following description and the appendedclams;

This invention is useful and applicable whenever it is desired'to ap 'lv to an article a very thin and evenly istributed nie tallic coating. In the preferred embodiment of the invention herein described it has been applied to the covering of copper wires with a coating of tin, but the invention is not limited' to the specific embodiment described which is susceptible to many variations and applications without de artinlg from its spirit and scope as set fort in t e appended c aims.

The practice of tinning metal surfaces which are to. be 4soldered is old and well known. Likewise it is an jold and universal practiceto tin wires, which are used in the construction of electric apparatus, before the wires are given a coatingo insulation. Consequently ever since the practicability of the baked enamel wire was established attempts have been made to develop a suitable and an eiiicient a paratus and method for producing tinne wire over which a smooth and evenly distributed surface of baked enamel could be applied. The development of this process was extremely diiiicult because the melting temperature of the coating metal tin, was somewhat lower than the temperatui-e required in the process of coating the wire with the bake enamel. Therefore when attempts were made to subject a tinned wire to a coating of baked enamel, the tinned coating on the surface of the wire would run into globules and form small horny projections of tin on the surface of the enameled wire. These horny projections in the process of coatin the wire with enamel would be covered with enamel, but in the subsequent handling of the wire the enamel on these projections would chip and break od'A and th-us' expose bare, uninsulated surfaces on the wire. As these uninsulated surfaces would develop in the handling and the working of the wire, the use of tinned enamel wire was rather unsatisfactory, as these bared spots in the Wire would frequently not manifest themselves until the wire had been used'in the manufacture of ap aratus.

t was, therefore, very desirable to devise a method and apparatus whereby a very thin coatin of tin could be applied to wire which wou d have no tendency to run when vsubjected to the temperature required for coating the tinned wire with a baked enamel. The herein described method and apparatus produces a tinned, baked enamel wire, which dll has a smooth even surface and on which the tin and enamel coatings are very evenly distributed and on which there are no bare or uninsulated spot-s.

The apparatus used in the application of the process is illustrated in the accompanying4 drawings, in which `igure 1 is a side elevation and Fig. 2 is a plan view of the complete machine; and

Fig. '3 illustrates a vertical section of the die housing showing the relative position I of the die in the metallic bath.

As illustrated in Figs. 1 and 2, the coinplete machine is composed of four units--a combined acid bathl and spool holder 1,-a tin bath 2, a Water bath 3 and a wire take-up mechanism 4. The acid bath as shown at 1 consists of a container 7 for holding the acid, in the bottom of which is placed a felt pad. vOn the right-hand side of the container are mounted a series of guiding posts 8 for guiding the wire under the roller 9 into the acid container 7. Extending up-v plurality of lead weights 16 equal in numer to the number of spools mounted on the upright member' 12. The lower surface of these lead weights is covered witha piece-of felt, and the lead weight in conJunction with this piece offelt serves to hold the wire fed throuoh the acid container in the acid between the felt pad mounted in the bottom of the container and the felt on the bottom of the lead weight 1 6. To the left of the acid container is mounted an acid removing means 18. Any`suitable means can be employed for this purpose, but in the device here illustrated a rubber wiper is used. A guide roller 20 is placed to theleft of the rubber wiper 18 over which the wire passes after leaving the rubber wiper.

The tinbath unit 2 comprises a housing 21 mounted on suitable standards and in which is placed a container 22 which holds the {iuid tin. To the right of the tin bath container 22 is mounted a roller 23, which serves to guide the wire on its way into the bath. Supported on the housing 21 is an adjustable arm 25 which carries a roller 26 and a die holder 27. is capable of movement in a vertical direction on the post 30. This movement of the adjustable arm is provided for convenbath.

This adjustable arm ience in Stringing the wire through the tin Thus when the arm 25 is moved to its extreme upward position, the die holder 27 and the roller 26 are removed from the tin bath, and the wire can be co-nveniently strung 'under the roller and through the die clamped in the holder. 27. The tin in the container. 22 may be heated and maintained in a molten condition by any well-known means.

^ In the preferred embodiment of the invention hereillustrated the heating of the container 22 is accomplished by a gas flame, the gas being supplied through the feed pipe 31. To the right ofthe die and supported on the housing 21 are another series of guiding posts 32 and the guide rollers 33 and 34.

The water unit 3 consists of a water container 36, in which is mounted a guide roller 37 which serves to ho-ld the wire immersed in the water as it passes through the water unit 3. Supported on the left face of the water unit 3 is a water removing means 39. This water removing means serves to dry the wire after it leaves the Water bath, and any suitable means may be employed for this purpose. A rubber` wiper such as shown as 39 has proved very satisfactory. The water in the water container 36 is constantlycirculated so as to cool the wire and also to more readily remove any trace of acid which may be left on the wire.

The wire take-up unit 4 is composed of suitable standards on which are supported a series of capstans, such as 41, around which the wire is fed and from where the wire is led to a suitable take-up spool, such as 42, on which the linished wire is wound. The capstans on the take-u belt driven by any suita le source of power,

such as 44, and the driving mechanismis so.

arranged that each capstan may be separately operated. Mounted between the cap stan 41 and the take-up spool 42 is a dis.-

mechanism 4 Aare lo a tributer 45 which serves to uniformly dis! i tribute the wire over 4the surface of the spool. rhe take-up spool42 is frictionally driven, thereby yproviding a tension which is practically uniform for winding the wire on the spools 42. The capstans 41 and the spools 42 are driven from the source of power 44 by any suitable means of belt or chain drive.

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A plurality of rollersl 47, one for each i wire, are attached to the right face of the water unit, 3. Each roller 47 is mounted on a bell crank 48 pivoted at 49. The lower end of each bell crank 49 is connected by any suitable means to a lever 52 which is pivoted at 53. Secured to the lever 52 is a spring 54 which serves as a brake for the spool 14. Thus, if one of the strands of wire should break, the bell crank associated with said wire, due to its weight, will drop by gravity, and by means of the connecting link 56. the lever 52 will be moved about its pivot 53,

raaancv and will apply the brake spring 54 to the feed spool 14. Consequently whenever a break occurs in a strand of wire, a brake will be applied to the associated feed spool and thus prevent further unrolling of the Wire and the tangle which would result from the continued feeding of wire after a strand had been broken.

Fig. 3 illustrates a vertical section of the die and the relative position of the die in the tin bath. The die 60 is mounted in a steel' ring 61, which in turn is mounted in a castiron housingy 59. This housing is clamped into the die holder 27 unitary wlth the lower part of the downwardl extending arm 25, by a set screw 62. The die proper 60 is placed in the iiuid tin so that 1t always remains submerged during the process of tinning the wire and in which process it acts to wipe the surplus tin from the wire as the wire leaves the tin bath. This die may be constructed of any exceedingly hard Vmaterial which can stand the severe use to which it is put. In the preferred form of this invention a diamond die has been used and its use has been very satisfactory, butthis invention is not limited to the use of a diamond die, as any other stones, and possibly some metals, would be hard enough to stand the severe use to which the die is subjected.

The process of coating wire by means of the apparatus which has been described in detail in the foregoing will now be considered. In this wire, the wire is first strung through the four units of the machine and the machine is then set into operation. Since each strand of wire is strung throughthe machine in the same manner, the description of this operation will be confined to one strandof wire. A spool containing copper wire to be tinned is placed on the spindle 14 and the wire is threaded through the guiding posts 8, under the roller 9 and throughthe acid container between the felt pads to the acid remover 18. From there the wire is fed over the rollers 20 and 23, under the roller 26, through the diamond die 60 and thence through the guiding posts 32, and over the rollers 33 and 34. In `Stringing this wire under the roller 26 and through the diamond die 60, the arm 25 is retained in its topmost position, in which position the roller 26 and the die 60 are not in contact with the molten tin. From the roller 34 the wire is fed under the roller 27 and roller 37 and thence through the water drying means 39, the capstans 41, about which two or three turns are taken, and then through the distributer 45 and on to the take-up spool 42.

When the six strands of wire'have been thus threaded through the machine, the six arms 25 are lowered so that the dies 60 will be immersed in the tin solution, as shown in' Fig. 3, it'being understood, ofcourse, that process of tinning coppery the t-in in the container 22 has been brought to a fluid state by means of a gas dame directed to the bottom of the container 22. After the dies have been lowered into the Huid tin, power is applied by means of the driving means 44, which, through suitable transmitting means, will turn the various capstans 41 and the take-u spools 42, and thus cause the drawing of t e wire from the delivery spools 14 through the units 1, 2, 3 and 4, as described above. The wire in passing. through the tin in the container 1s thoroughly covered with tin, and in its passage through the die 60 the surplus tin is removed from the wire, leaving a very thin, uniformly distributed coating of tin on the copper wire. This coating on the copper wire is so thin that it approximates only about three milligrams per square inch. The die 60 contained in the tinnin bath is bored to the size of the wire which 1s ultimately desired and consequently if the wire which is being tinned is the exact size of the ultimately desired coated or tinned wire,

then the coated wire in leaving the tin bath `will be subjected to a ver slight drawing operation, in addition to t e wlping operation, because of the thin film of tin with which the wire is coated. In the o erationA of this process it has been found esirahle to use an uncoated copper wire which is slightly over size-that is a wire whose gage is Just slightly greater than the gage of the desired coated wire. When an over sized wire of this kind is used, it is obvious that the drawing operation in the die 60 is somewhat greater than when an uncoated Wire of the gage of the ultimate coated wire is used. The use of an oversized wire is not essential, and satisfactory results can be obtained with wire drawn to a gage equal to the gage of the ultimately desired coated w1re. A

In this process of coating copper wire with tin, each strand of wire .1s drawn through the tin at a rate of about 500 feet per minute and the operation is continuous until all the bare copper wireis removed from the supply spool 14 and the tinned copper wire is wound on the take-up spool 42.

When the wire has thus been tinned and wound on the spool 42, the spool 42 is removed from the take-up mechanism and placed on the supply spindle of a machine designed for coating wires with insulating enamel. A machine for this purpose is disclosed and described in U. S. Patent to Gr. Gustave, No. 1,004,251. The tinned copper wire wound on spool 42 of the unit 4 of Fig. 1 is then given the treatment disclosed in said patent. In this process of coating wire with baked enamel, the wire is subjected to a temperature which is equal to or slightlyhigher than the melting point of tin. For this reason when it is attempted to coat wire tinned in the ordinary manner with a coating of baked enamel, the tin has a tendency to run and form in globules on the wire. These globules in the coating process result in thornyprojections on the surface of the wire from which the enamel coating will readily chipV and thereby, surtaces of bare wire are exposed. Further, this tendency of the tin to run results in a very uneven, rough coating of enamel. However, when wire as tinned -by the process as above described, is subjected to an enamel baking process of the kind described in the aforesaid patent, the tin has v,no tend- `enc to run, and the resu-lting enameled wire is c elivered from the baking furnace with an even, smooth surface of baked enamel over the coatin of tin, which latter coating is not distur ed in the least by the baking process.

n the description of the apparatus for applying this improved process a preferred embodiment has been described, but obviously this invention is not limited to that specific embodiment, but is ca able of many variations and applications without departing from its spirit and scope as outlined in the following claims.

What is claimed is:

l. The process of coating wires with a coating of another metal which consists in subjecting the wire to a bath oi the coating metal and then drawing the coated wire through a die of a smaller gage than that of the uncoated wire. I

2. The process of covering copper wires with a coating of tin which consists in subjecting the wire to a molten tin bath and then drawing the coated tinned wire through a wiping die of the gage of the uncoated wire to exert a drawing eiiect upon the coated wire and, thereby applying to the copper wire an exceedingly thin coat of tin.

3. The process of coatin wires with a coating of another metal w ich consists in subjecting the wire to a bath of the coating metal and then drawing theI coated wire through a die which is maintained submerged in the bath of the coating metal.

4. The process of covering copper wires with a coating of tin which consists in subjecting the copper wire to a molten tin bath and then drawing the coated tinned wire through a wiping die which is maintained submerged in the tin bath.

5. The method4 of producing wires covered with a coating of another metal of a desired size or gage which consists in subjecting an over size uncoa'ted wire to a bath oi the coating metal and then drawing the coated conductor through a vdie of the desired size.

6. The method of producing tinned copper wire'of a desired size or gage which consistsinf subjecting an over size copper wire to a bath of tin and then drawing the tinned c opper wire through a die of the desired s1ze.

7. The process of covering wires with a very thin, fine, evenly distributed coatingof metal and insulating enamel, which consists in subjecting the wire to a bath of the coatin metal, then drawing the coated wire through a die of a smaller age than the uncoated wire and finally subjecting the metal so coated to a bath of insulating enamel.

8. The process of covering copper wires with a fine coating of tin which consists in passing the `copper wire through an acid bath, removing the acid from the wire, then subjecting the wire to a bath of fluid tin and finally drawin the tinned wire through a die of a size slig tly smaller than the size of the original copper wire.

9. The process of covering copper wires with a very thin primary coatin of tin and a secondary coating lof insulating enamel, which consists in treating the copper to a bath of fluid tin, then drawing the tinned copper wire through a die to a size smaller than 4the original copper wire and finally subjecting the tinned wire to a bath of the insulating enamel.

10. The process of covering copper wire with a very thin, primary coating of tin and secondary coating of insulating enamel, which consists in treating the copper wire to a bath of molten tin, then drawing the tinned copper wire through a die to a size smaller than the original copper wire and finally subjecting the tinned wire to a bath of the insulating enamel at a temperature equal to, or higher than the melting point of tin.

11. The method of providing a metal article with an exceedingly thin coating of another metal, which consists in passing the article to be coated through a bath of the coating metal and then drawing the coated article through a die to produce the desired size.

12. The process of producing a tinned copper wire having an outside coating of insulating enamel, which consists in subjecting the copper wire to a fluid bath of tin and then drawing the coated wire through a die to reduce the tinned coating to a degree of thinness which will prevent the running of the tin coating when the coated wire is treated with a coating of insulatingenamel at a temperature exceeding that of the melting point of tin.

13. In a machine for coating wire with another metal the combination with a wire feeding mechanism, of an acid bath Iand acid removing device for cleaningthe wire, a

metal bath for coating the wire, a die for maaier 14. ln a machine for coating wire, the combination with a wire feeding means, of a metal coating means and a die for drawing thevcoated wire to the desired size.

15. In a machine for coatin copper wire, the combination of an acid bath and acid removing means for v cleaning the wire, a tin bath for coating. the

wire, a die for drawing the tinned copper' wire to the desired size, a water bath, a water removing means and a wire take-up mechanism for receiving the finished wire.

16. In a machine for coating wire, a wire feeding means, a wirel guiding means whereby the wire is guided through, an acid bath, an acid removing means, a metal bath for coating the wire, a die for `drawing the vcoated wire to the desired size, a water bath,

a water removing means and a wire take-up means for receiving the finished wire.

17. In a machine for tinning copper wire, a combination with a wire feeding means and a wire guiding means whereby the co per wire is guided'through, an acid bath,

with a wire eeding means,

an acid removing means, a tin bath for tinning the wire, a die for drawing the tinneol copper wire to the desired size, a water bath, a water removing means and a wiref take-up means for receiving the coated wire.

18. lln a machine for simultaneously tinning a plurality of copper wires, the combination with wlre feeding means, of means for guiding said wires, a tinning bath for said wires, a plurality of dies one for each wire for drawing thetinned copper wire to the size desired, and a wire take-up mechanism comprising means for uniformly drawing the wires from the feeding means It)hrough the guiding means and the tinning ath.

lln witness whereof, I hereunto subscribe 'my name thisl twenty eight day of July JOSEPH n. Harrrawav.

Witnesses:

L. A. Monnmnn, H. D. KEMP. 

